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Explain Lava Field

Lava Field Explained!

Lava Field Technical Terms

Lava Field: An area covered primarily by lava flows whose terrain can be rough and broken or relatively smooth; it can include vent structures (e.g., small cinder cones, spatter cones, etc.), surface flow structures (e.g., pressure ridges, tumuli, etc.) and small, intermittent areas covered with pyroclastics. Compare – lava plain, volcanic field. SW

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Expose Lava Flow

Lava Flow Exposed!

Lava Flow Technical Terms

Lava Flow: A solidified body of rock formed from the lateral, surficial outpouring of molten lava from a vent or fissure, often lobate in form. Compare - `a`a lava flow, lava flow unit, pahoehoe lava flow. GG

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Discover Lava Plain

Lava Plain Discovered!

Lava Plain Technical Terms

Lava Plain: A broad area of nearly level land, that can be localized but is commonly hundreds of square kilometers in extent, covered by a relatively thin succession of primarily basaltic lava flows resulting from fissure eruptions. Compare – lava plateau, lava field, volcanic field. SW & GG

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Explain Lava Flow Unit

Lava Flow Unit Explained!

Lava Flow Unit Technical Terms

Lava Flow Unit: A separate, distinct lobe of lava that issues from the main body of a lava flow; a specific outpouring of lava, a few centimeters to several meters thick and of variable lateral extent that forms a subdivision within a single flow. A series of overlapping lava flow-units together comprise a single lava flow. Also called flow unit. Compare – lava flow. GS & GG

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Explain Lava Plateau

Lava Plateau Explained!

Lava Plateau Technical Terms

Lava Plateau: A broad elevated tableland or flat-topped highland that may be localized but commonly is many hundreds or thousands of square kilometers in extent, underlain by a thick succession of basaltic lava flows resulting from fissure eruptions (e.g. Columbia River Plateau). Compare – lava plain, lava field. GG

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Expose Lava Trench

Lava Trench Exposed!

Lava Trench Technical Terms

Lava Trench: A natural surface channel in a lava flow that never had a roof, formed by the surficial draining of molten lava rather than by erosion from running water; also called lava channel. Compare – mawae, lava tube. SW

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Remember Lava Tube

Lava Tube Remembered!

Lava Tube Technical Terms

Lava Tube: A natural, hollow tunnel beneath the surface of a solidified lava flow through which the lava flow was fed; the tunnel was left empty when the molten lava drained out. MA & GG

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Explain Ledge

Ledge Explained!

Ledge Technical Terms

Ledge: A narrow shelf or projection of rock, much longer than wide, formed on a rock wall or cliff face, as along a coast by differential wave action on softer rocks; erosion is by combined biological and chemical weathering. (b) A rocky outcrop; solid rock. (c) A shelf-like quarry exposure or natural rock outcrop. Compare - structural bench. GG

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Discover Lee

Lee Discovered!

Lee Technical Terms

Lee: Said of a side or slope that faces away from an advancing glacier or ice sheet, and facing the downstream (“down-ice”) side of a glacier and relatively protected from its abrasive action. Compare – stoss, stoss and lee, crag and tail. GG

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Expose Levee

Levee Exposed!

Levee Technical Terms

Levee: An artificial or natural embankment built along the margin of a watercourse or an arm of the sea, to protect land from inundation or to confine streamflow to its channel. Compare artificial levee, natural levee. GG

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Discover Leveled Land

Leveled Land Discovered!

Leveled Land Technical Terms

Leveled Land: A land area, usually a field, that has been mechanically flattened or smoothed to facilitate management practices such as flood irrigation; as a result the natural soil has been partially or completely modified (e.g., truncated or buried). SW

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Expose Limestone

Limestone Exposed!

Limestone Technical Terms

Limestone: A sedimentary rock consisting chiefly (more than 50 percent) of calcium carbonate, primarily in the form of calcite. Limestones are usually formed by a combination of organic and inorganic processes and include chemical and clastic (soluble and insoluble) constituents; many contain fossils. HP

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Discover Linear Gilgai

Linear Gilgai Discovered!

Linear Gilgai Technical Terms

Linear Gilgai: A type of gilgai dominated by parallel micro-low troughs separated by low ridges (micro-highs) and oriented perpendicular to the topographic contour (i.e., up and down slopes); the prevailing type of gilgai on sloping terrain (slopes > 8 %). Compare – circular gilgai, elliptical gilgai, gilgai. SW

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Discover Lithification

Lithification Discovered!

Lithification Technical Terms

Lithification: The conversion of unconsolidated sediment into a coherent and solid rock, involving processes such as cementation, compaction, desiccation, crystallization, recrystallization, and compression. It may occur concurrently with, shortly after, or long after deposition. HP

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Discover Local Relief

Local Relief Discovered!

Local Relief Technical Terms

Local Relief: A general term referring to the prevailing difference in elevation between the lowest and highest parts of the landscape at a given locale (e.g. the average difference in elevation between a representative portion of a valley floor and the tops of the bounding valley walls). SW

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Remember Lodgment Till

Lodgment Till Remembered!

Lodgment Till Technical Terms

Lodgment Till: A basal till commonly characterized by compact, fissile ("platy") structure and containing coarse fragments oriented with their long axes generally parallel to the direction of ice movement. Compare - till, flow-till, melt-out till. GG

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Explain Loess

Loess Explained!

Loess Technical Terms

Loess: Material transported and deposited by wind and consisting predominantly of silt-size particles. Commonly a loess deposit thins and the mean-particle size decreases as distance from the source area increases. Loess sources are dominantly from either glacial meltwaters (i.e. “cold loess”) or from non-glacial, arid environments, such as deserts (i.e. ”hot loess”). [soil survey] Several types of loess deposits can be recognized based on mineralogical composition (calcareous loess, non-calcareous loess). SW & GSST

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Explain Loess Bluff

Loess Bluff Explained!

Loess Bluff Technical Terms

Loess Bluff: A bluff composed of a thick deposit of coarse loess, formed immediately adjacent to the edges of flood plains, as along the Mississippi River valley or China. Sometimes referred to as a bluff formation (not preferred). SW & GG.

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Explain Loess Hill

Loess Hill Explained!

Loess Hill Technical Terms

Loess Hill: A hill composed of thick deposits of loess, as in IA, MO, NE and the Palouse Hills of WA & ID. SW

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Discover Log Landing

Log Landing Discovered!

Log Landing Technical Terms

Log Landing: A comparatively level area, usually with road access, constructed or cut into steeper slopes and used for sorting logs during timber harvest operations. Compare – skid trail. SW

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Remember Longitudinal Dune

Longitudinal Dune Remembered!

Longitudinal Dune Technical Terms

Longitudinal Dune: A long, narrow sand dune, usually symmetrical in cross profile, oriented parallel to the prevailing wind direction ; it is wider and steeper on the windward side but tapers to a point on the lee side. It commonly forms behind an obstacle in an area where sand is abundant and the wind is strong and constant. Such dunes can be a few meters high and up to 100 km long. Compare – seif dune, transverse dune. GG

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Expose Louderback

Louderback Exposed!

Louderback Technical Terms

Louderback: A hill or ridge composed of a lava flow remnant that caps or is exposed in a tilted fault block and bounded by a dip slope. Used as evidence of block faulting in Basin-and-Range terrain (western USA). Compare – hogback. GG

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Remember Low-Center Polygon

Low-Center Polygon Remembered!

Low-Center Polygon Technical Terms

Low-Center Polygon: A polygon whose center is depressed relative to its boundary. Compare - high-center polygon. NRC

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Discover Low Hill

Low Hill Discovered!

Low Hill Technical Terms

Low Hill: A generic name for an elevated, generally rounded land surface with low local relief, rising between 30 meters (100 ft.) to as much as 90 m (approx. 300 ft.) above surrounding lowlands. Compare – high hill, hill, hillock. SW

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Expose Lowland

Lowland Exposed!

Lowland Technical Terms

Lowland: An informal, generic, imprecise term for low-lying land or an extensive region of low-lying land, especially near a coast and including the extended plains or country lying not far above tide level. (b) (not preferred) A generic, imprecise term for a landscape of low, comparatively level ground of a region or local area, in contrast with the adjacent higher country. (c) (not recommended – use valley, bolson, etc.) A generic term for a large valley. Compare - upland. SW

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Remember Low Marsh

Low Marsh Remembered!

Low Marsh Technical Terms

Low Marsh: (refer to mud flat). The flat, usually bare ground situated seaward of a salt marsh and regularly covered and uncovered by the tide; e.g., a mud flat. GG

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Expose Mafic Rock

Mafic Rock Exposed!

Mafic Rock Technical Terms

Mafic Rock: A general term for igneous rock composed chiefly of one or more ferromagnesian, dark-colored minerals; also said of those minerals. Compare - felsic rock. GG

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Discover Mainland Cove

Mainland Cove Discovered!

Mainland Cove Technical Terms

Mainland Cove: A subaqueous area adjacent to the mainland or a submerged mainland beach that forms a minor recess or embayment within the larger basin. Compare – cove, barrier cove. SSS

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Expose Maar

Maar Exposed!

Maar Technical Terms

Maar: A low relief, broad volcanic crater formed by multiple, shallow explosive eruptions. It is surrounded by a crater ring in the form of low ramparts of gently dipping (i.e. < 25 degrees), well-bedded ejecta; may be partially or completely filled by water (maar lake). SW & GG

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Discover Lowmoor Bog

Lowmoor Bog Discovered!

Lowmoor Bog Technical Terms

Lowmoor Bog: A bog that is at or only slightly above the water table, on which it depends for accumulation and preservation of peat (chiefly the remains of sedges, reeds, shrubs, and various mosses). Compare - highmoor bog, raised bog. GG

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Expose Lateral Spread

Lateral Spread Exposed!

Lateral Spread Technical Terms

Lateral Spread: A category of mass movement processes, associated sediments (lateral spread deposit) or resultant landforms characterized by a very rapid spread dominated by lateral movement in a soil or fractured rock mass resulting from liquefaction or plastic flow of underlying materials; also called spread. Types of lateral spreads can be specified based on the dominant particle size of sediments (i.e. debris spread, earth spread, rock spread. Compare – fall, topple, slide, flow, complex landslide, landslide. SW, DV & GG

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Explain Lapilli

Lapilli Explained!

Lapilli Technical Terms

Lapilli: Non or slightly vesicular pyroclastics, 2.0 to 76 mm in at least one dimension, with an apparent specific gravity of 2.0 or more. Compare - ash [volcanic], block [volcanic], cinders, tephra. KST

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Discover Land-Surface Form

Land-Surface Form Discovered!

Land-Surface Form Technical Terms

Land-Surface Form: The description of a given terrain unit based on empirical analysis of the land surface rather than interpretation of genetic factors. Surface form may be expressed quantitatively in terms of vertical and planimetric slope-class distribution, local and absolute relief, and patterns of terrain features such as interfluve crests, drainage lines, or escarpments. HP

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Discover Landslide

Landslide Discovered!

Landslide Technical Terms

Landslide: A general, encompassing term for most types of mass movement landforms and processes involving the downslope transport and outward deposition of soil and rock materials, caused by gravitational forces and which may or may not involve saturated materials. Names of landslide types generally reflect the dominant process and/or the resultant landform. The main operational categories of mass movement are fall (rockfall, debris fall, soil fall), topple (rock topple, debris topple, soil topple), slide (rotational landslide, block glide, debris slide, lateral spread), flow [rock fragment flow (especially rockfall avalanche), debris avalanche, debris flow (e.g., lahar), earthflow, (creep, mudflow)], and complex landslides. Compare – solifluction. SW & DV

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Remember Landscape

Landscape Remembered!

Landscape Technical Terms

Landscape: A broad or unique land area comprised of an assemblage or collection of landforms that define a general geomorphic form or setting (e.g., mountain range, lake plain, lava plateau, or loess hill) Landforms within a landscape are spatially associated, but may vary in formation processes and age. SW & GSST

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Explain Landform

Landform Explained!

Landform Technical Terms

Landform: Any physical, recognizable form or feature on the earth's surface, having a characteristic shape, internal composition, and produced by natural causes; a distinct individual produced by a set of processes. Landforms can span a large size (e.g., dune encompasses a number of feature including parabolic dune, which is tens-of-meters across and seif dune, which can be up to a 100 kilometers across. Landforms provide an empirical description of the earth's surface features. SW & GG

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Explain Lamina

Lamina Explained!

Lamina Technical Terms

Lamina: (noun) The thinnest recognizable layer (commonly < 1 cm thick) of original deposition in a sediment or sedimentary rock, differing from other layers in color, composition, or particle size. Several laminae constitute a bed. Compare - lamella. GG

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Explain Lake Terrace

Lake Terrace Explained!

Lake Terrace Technical Terms

Lake Terrace: A narrow shelf, partly cut and partly built, produced along a lake shore in front of a scarp line of low cliffs and later exposed when the water level falls. GG

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Remember Intrusive

Intrusive Remembered!

Intrusive Technical Terms

Intrusive: Denoting igneous rocks derived from molten matter (magmas) that invaded pre-existing rocks and cooled below the surface of the earth. Compare - extrusive. HP

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Remember Lakeshore

Lakeshore Remembered!

Lakeshore Technical Terms

Lakeshore: The narrow strip of land in contact with or bordering a lake; especially the beach of a lake. GG

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Explain Lake Plain

Lake Plain Explained!

Lake Plain Technical Terms

Lake Plain: A nearly level surface marking the floor of an extinct lake filled by well-sorted, generally fine-textured, stratified deposits, commonly containing varves. GG

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Remember Lake

Lake Remembered!

Lake Technical Terms

Lake: An inland body of permanently standing water fresh or saline, occupying a depression on the Earth’s surface, generally of appreciable size (larger than a pond) and too deep to permit vegetation (excluding subaqueous vegetation) to take root completely across the expanse of water. GG

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Expose Lagoonal Deposit

Lagoonal Deposit Exposed!

Lagoonal Deposit Technical Terms

Lagoonal Deposit: Sand, silt or clay-sized sediments transported and deposited by wind, currents, and storm washover in the relatively low-energy, brackish to saline, shallow waters of a lagoon. Compare – estuarine deposit, fluviomarine deposit, marine deposit. SSS

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Remember lagoon channel

lagoon channel Remembered!

lagoon channel Technical Terms

lagoon channel: A subaqueous, sinuous area within a lagoon that likely represents a relict channel (paleochannel) (Wells et al., 1994) that is maintained by strong currents during tidal cycles (Short, 1975). SSS

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Explain Lagoon Bottom

Lagoon Bottom Explained!

Lagoon Bottom Technical Terms

Lagoon Bottom: The nearly level or slightly undulating central portion of a submerged, low-energy, depositional estuarine basin (McGinn, 1982) characterized by relatively deep water (1.0 to >2.5 m). Compare – bay bottom. SSS

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Remember Lagoon

Lagoon Remembered!

Lagoon Technical Terms

Lagoon: A shallow stretch of salt or brackish water, partly or completely separated from a sea or lake by an offshore reef, barrier island, sandbank or spit. GG‘87. [relict landform] A nearly level, filled trough or depression behind the longshore bar on a barrier beach and built by a receding pluvial or glacial lake. Compare - sewage lagoon. FFP

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Expose Kegel Karst

Kegel Karst Exposed!

Kegel Karst Technical Terms

Kegel Karst: A general name used to describe several types of humid tropical karst landscapes characterized by numerous, closely spaced cone- (cone karst), hemispherical- (halbkugelkarst), or tower-shaped (tower karst) hills with vertical or near-vertical walls and having intervening closed depressions and narrow steep-walled karst valleys or passageways. Compare – cockpit karst. GG & SW

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Expose Kegel Karst

Kegel Karst Exposed!

Kegel Karst Technical Terms

Kegel Karst: A general name used to describe several types of humid tropical karst landscapes characterized by numerous, closely spaced cone- (cone karst), hemispherical- (halbkugelkarst), or tower-shaped (tower karst) hills with vertical or near-vertical walls and having intervening closed depressions and narrow steep-walled karst valleys or passageways. Compare – cockpit karst. GG & SW

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Expose Karst Valley

Karst Valley Exposed!

Karst Valley Technical Terms

Karst Valley: A closed depression formed by the coalescence of multiple sinkholes; an elongate, solutional valley. Its drainage is subsurface, diameters range from several hundred meters to a few kilometers, and it usually has a scalloped margin inherited from the sinkholes. It may have nominal, local channel flow (small streams), sequential sinkhole inlets (springs) and outlets (swallow hole, etc.); also called compound sinkhole (not preferred), uvala (not preferred). Compare – sinkhole, interior valley. SW & GG

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Expose Karst Tower

Karst Tower Exposed!

Karst Tower Technical Terms

Karst Tower: An isolated, separate hill or ridge in a karst region consisting of an erosional remnant of limestone or other sedimentary rocks with vertical or near-vertical, convex side slopes and commonly surrounded by an alluvial plain, lagoon, or deep rugged ravines. Compare – mogote, karst cone. SW